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Deviation-angle and trajectory statistics for inertial particles in turbulence

Bhatnagar, Akshay and Gupta, Anupam and Mitra, Dhrubaditya and Perlekar, Prasad and Wilkinson, Michael and Pandit, Rahul (2016) Deviation-angle and trajectory statistics for inertial particles in turbulence. In: PHYSICAL REVIEW E, 94 (6).

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Official URL: http://dx.doi.org/10.1103/PhysRevE.94.063112

Abstract

Small particles in suspension in a turbulent fluid have trajectories that do not follow the pathlines of the flow exactly. We investigate the statistics of the angle of deviation phi between the particle and fluid velocities. We show that, when the effects of particle inertia are small, the probability distribution function (PDF) P-phi of this deviation angle shows a power-law region in which P-phi similar to phi(-4). We also find that the PDFs of the trajectory curvature. and modulus theta of the torsion theta have power-law tails that scale, respectively, as P-kappa similar to kappa (-5/2), as kappa -> infinity, and P-phi similar to phi(-3), as theta -> infinity: These exponents are in agreement with those previously observed for fluid pathlines. We propose a way to measure the complexity of heavy-particle trajectories by the number N-I(t, St) of points (up until time t) at which the torsion changes sign. We present numerical evidence that n(I)(St) lim(t ->infinity) N-I(t, St)/t similar to St(-Delta) for large St, with Lambda similar or equal to 0.5.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to theAMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Depositing User: Id for Latest eprints
Date Deposited: 26 Apr 2017 07:22
Last Modified: 26 Apr 2017 07:22
URI: http://eprints.iisc.ac.in/id/eprint/56625

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